1. Field of Invention
This invention relates to a mastication article, principally for domestic animals, and more particularly to a mastication article having a microbe-inhibiting agent or property that substantially inhibits the proliferation of microbes on, within, or around the mastication article. The term "microbe" herein refers broadly to classes of bacteria, viruses, germs, molds, mildew, fungi, allergens, and other microorganisms. An article of the present invention provides both comfort and health benefits to both pets and people involved with the use of such an article.
2. Description of the Related Art
Mastication articles are very popular with pets, and especially so with dogs. There are two basic types of mastication articles: digestible and non-digestible. The prototypical digestible type is "rawhide" or rawhide-derived; but starch- or seed-based or other digestible materials may be used as well. The non-digestible type is more variegated, and may include alone or in part components comprised of molded plastic, rope, textile fabrics, fiber-fill, foam, as well as other components.
Mastication articles can provide therapeutic as well as amusement value to the pets that chew on them. The mastication provides a degree of exercise and cleans and massages the teeth and gums of the pet; and, pets (especially dogs) seem to enjoy mastication on things. In addition, giving pets desirable articles on which to chew may preclude them from mastication on other things that may be harmful to them or would upset the pet's owner.
Mastication articles for pets tend to become messy and unsanitary as the pets chew on them. There is also a risk of microbial proliferation on or within the mastication articles during their storage. Both of these factors are especially problematic for digestible mastication articles, which provide ample nutritional resources for the abundant proliferation of microbes. It is therefore useful and valuable to provide sanitary mastication articles that are resistant to the proliferation of microbes and optionally to odors. Because pets chew continually upon these articles, and because pets can eventually digest these articles (even when they are not intended for digestion), toxicity considerations with regard to the microbe-inhibiting treatment are important.
Of the digestible type, rawhide is the most popular type of mastication article. Ready-to-use rawhide may be acquired commercially in a variety of forms and is manufactured from animal (preferably cattle) hides by methods known in the Art (see, e.g., U.S. Pat. No. 5,114,704). The manufacturing process generally consists of several steps. After the raw hides are obtained, they are usually treated in a lime-based solution (liming), the primary object of which is to loosen the hair on the hide. To the solution may be added ammonium salts, sodium sulfide, or other additives. After the liming treatment, the hair is removed from the hide, either by hand or using a dehairing machine. In the next step, known as "fleshing," tissue is removed from the flesh side of the hide. This may be performed with a special knife or with a fleshing machine. It is then necessary to ensure that all of the lime is removed from the hide. Washing in water can remove much of the lime, but it is generally necessary to use a more aggressive treatment with acids or acid salts to remove the remainder.
After the hides are dehaired, fleshed, and cleaned, they may be cut into the desired shapes and manipulated. Drying may be done in ambient air or preferably in an oven at elevated temperatures (usually less than 150.degree. C.).
U.S. Pat. No. 5,310,541 discloses a rawhide animal chew intended to inhibit oral pathogens from proliferating in a dog's mouth. The rawhide is treated with enzymes that are released into the dog's saliva upon mastication. Once in the dog's saliva, these enzymes set off a chain of reactions that attack oral pathogens present in the dog's mouth. Thiocyanate and iodide additives may optionally be added to enhance this effect.
U.S. Pat. No. 5,476,069 discloses a molded rawhide mastication article, in which rawhide is ground into small pieces and then injection molded at high temperature and pressure. The addition of casein and gelatin before injection are said to facilitate molding.
U.S. Pat. No. 4,419,372 discloses a simulated rawhide mastication article in which a mixture comprising an oil seed protein, a polyol plasticizer, lecithin, and water are extruded into a ribbon. The ribbon is then "sandblasted" (e.g., using ground walnet) to impart a rawhide-like texture to the surface. The material is then shaped or cut in a manner similar to those of real rawhides.
U.S. Pat. No. 5,407,661 discloses a digestible mastication article for a pet in which a starch, a cellulosic fibrous material (e.g., corn cob fractions), a humectant, a proteinacious binder and a tarter-control oral care additive are mixed together and extruded in such a manner that the extrudate possesses an open, cellular structure.
U.S. Pat. No. 5,419,283 discloses a molded mastication article for an animal comprising a starch material and a biodegradable ethylene copolymer. Other edible materials can be added as plasticizers or as lubricants. These materials are mixed in the presence of water for subsequent injection molding into desired shapes (e.g., a bone).
Mastication articles of the non-digestible type are considerably more variegated than those of the digestible type. They may be comprised of solid molded plastic, hollow molded plastic, textile fabrics, rope-materials, synthetic or natural fiber-fill, foams, etc. They generally possess a texture and structure that combine to create a desirable "mouth-feel" for the pet. This feature is especially important if the article possesses no attractants (e.g., a meat scent).
U.S. Pat. No. 4,557,219 discloses a molded polyurethane mastication article for a pet in which has been incorporated a surface-migrating flavoring extract.
U.S. Pat. No. 5,477,815 discloses a mastication article for a dog comprising a composite rope, in which an inner core of the rope comprises brittle, frangible, and non-water absorbing threads (optionally with a flavoring extract), and the outer shell comprises soft, pliable cotton. The inner core is said to give the article a "crunchy" sound and texture and to aid in the dog's passing of the article if it should be eaten. It is said that the non-water-absorbency of the inner core material promotes faster drying of the outer water-absorbing cotton material; and it thereby inhibits bacterial growth in the cotton. U.S. Pat. No. 5,467,741 discloses a similar mastication article, but includes the incorporation of therapeutic dental agents and/or breath-freshening agents in the inner core.
U.S. Pat. No. 5,477,815 discloses a molded bone-shaped mastication article that has relatively sharp, conically-shaped spikes distributed over its surface. The spikes are said to remove tartar or plaque from the dog's teeth as the dog chews on the toy. The mastication articles is a rigid polymer, such as a rigid polyurethane or a rigid polyamide. A meat scent or flavor is optionally added to the article to increase its attractiveness to dogs.
U.S. Pat. No. 5,477,815 discloses a molded dog mastication article which is constructed from a synthetic thermoplastic material (e.g., polyurethane) in which an animal meal (e.g., chicken meal, fish meal, etc.) has been incorporated prior the molding process.
U.S. Pat. No. 5,477,815 discloses a molded dog mastication article comprising water absorbing nylon in which at least a surface layer has been incorporated with sugar.
Despite the desirability of effective microbe-inhibiting mastication articles for pets, there have been no practical solutions that would provide effective and continual protection against microbial proliferation in or on the articles. The only two disclosures which even remotely relate to microbe inhibition are the aforementioned U.S. Pat. No. 5,477,815, which only relates to enhanced drying of a rope-based article to shorten the period of time it is most susceptible to microbial proliferation; and U.S. Pat. No. 5,310,541, in which the rawhide is a carrier for an enzyme to be released into a dog's mouth. In the latter invention, the rawhide is only a vehicle for delivering a reaction-initiating enzyme into the dog's mouth. The enzyme, which is inactive with respect to microbes, reacts with the salivary solution in the dog's mouth, ultimately resulting in the temporary creation of ions in solution which attack oral pathogens in the dog's mouth; and these ions can exist only in the dog's saliva. The rawhide article itself therefore contains no species that will inhibit subsequent microbial proliferation in and on the article (any such species which are transferred to the article from the dog's saliva will soon dry-up and thus become ineffective).
Thus, there is a need in the art for mastication articles for pets, where the proliferation of microbes is prevented in and on the articles; where the microbe-inhibiting properties of the articles are continually active and durable; where these articles are desirable and attractive to the pets for which they are intended; and where these articles are safe for pets and humans.